The vast improvement of the medical imaging and localization technology over the recent past has brought a challenge to physics and computer technology to extend the computerized treatment simulation (planning and optimization) capabilities. The capability to calculate the distribution of absorbed dose produced by photon beams and electron beams to the most general characteristics is fundamental to radiotherapy. Our photon and electron beam radiation field models have been described before. An important advantage of these models is that they require relatively few experimental data and thus can be implemented very easily. Expansion of our beam treatment planning program Mac TPS on Macintosh equipment is continuing. The system is being evaluated in parallel to the existing Vax-750 based system for "conventional" multi-slice planning. 3-D segmented imaging is being applied extensively now, and is being continually expanded, guided by new demands and suggestions from the medical staff. The is a growing interest in the community. An extensive manual with several levels of user guidance is available and is kept up- to-date. The experimental project with DCRT to explore the potential of connecting our Mac II system to a massive parallel processing system to alleviate this aspect is slowly progressing. The project faces major problems with the real-time 2-way transmission of very large amounts of data. The problems will be present for a while. Adequate staffing is also a major problem.